This invention relates to a method for molding an elastic head for a doll and a mold therefor.
Conventionally, an elastic head for a doll has been generally formed of molten vinyl chloride by slush molding or rotational molding. Both slush molding and rotational molding prevent formation of such a parting line as seen in a molded doll head made by blow molding, to thereby provide a molded article satisfactorily finished. Also, rotational molding has the advantage of enabling mass production of the head at a low cost.
Vinyl chloride contains chlorine and the above-described molding techniques require to adding phthalate ester to act as a plasticizer to vinyl chloride in order to provide a molded article with elasticity or resiliency. Recently, safety of vinyl chloride and phthalate ester has been considered to be problematic, thus, use of vinyl chloride tends to be avoided in various fields. This is likewise true of a doll head, thus, it is required that the head be formed of a safe molding material.
However, molding of a molding material other than vinyl chloride by slush molding or rotational molding is substantially impossible because the material fails to be gelled. Blow molding permits molding of the material, however, it fails to prevent formation of a parting line on a surface of a molded head. Also, it fails to permit the molding material to be satisfactorily distributed to fine uneven portions such as eyes of the doll head, its nose, its mouth and the like, so that there is a possibility of failing to mold the head exactly in conformity to a configuration of a mold. In manufacturing of a doll head, satisfactory finishing of a surface of a face of the head such as increased smoothness of the surface and enhanced elaborateness of unevenness of various parts of the face are absolute requirements. The conventional blow molding techniques fully fail to meet both requirements.
Also, a head for a doll is required to exhibit elasticity which permits the head to have a soft feel like the human skin. Thus, the head must meet such a requirement.
The present invention has been made so as to solve the above-described problem of the prior art. Accordingly, it is an object of the present invention to provide a method for forming a doll head and a mold therefor which is capable of employing a molding material other than vinyl chloride and forming the head for exactly conforming or corresponding to a configuration of a mold by blow molding as well as permitting the doll head to exhibit elasticity.
In order to solve the above-described problem of the prior art, in accordance with the present invention, a method for molding a head for a doll is provided. The method is characterized in that the method comprises the steps of: providing a split mold having an inner surface formed to have a configuration conforming to a shape of the head of the doll, the split mold having a parting line formed on a hairline of the hair of the head or in proximity thereto; heating a parison constituted by a molding material which mainly consists of one of a thermoplastic synthetic resin elastomer and silicone resin and which has a plasticizer and a coloring agent added thereto, dropping in the parison between mold members of the split mold kept spaced from each other, then joining the mold members of the split mold together, and blowing air into the split mold thus joined; removing air from a cavity defined in the split mold through at least one of projections formed on the inner surface of the split mold when air is blown into the split mold; and separating the mold members of the split mold from each other to remove a molded article therefrom.
Such construction of the method of the present invention effectively prevents the parting line from appearing on a face which is the most important portion of the doll head. The parting line is defined on a hairline of the hair of the head or in proximity thereto. The head is covered with hair embedded on the head or a wig, so that the parting line may be prevented from being viewed from the outside or outwardly exposed. In the prior art, a post-treatment of a parting line formed on an elastic molded article is manually carried out, resulting in the molding being highly troublesome. The present invention eliminates such a troublesome treatment, so that the head may be manufactured with increased efficiency.
Further, in the present invention, air is removed from the cavity in the split mold through an air vent hole formed in at least one of the projections, such as a nose or the like, of the split mold substantially concurrently with blowing of air which is carried out during the molding, to thereby ensure that the molding material is satisfactorily fed or distributed to the projections. Thus, portions of the head corresponding to the projections are each permitted to be formed to have a distinct shape exactly conforming to a configuration of the mold.
In addition, the molding material is constituted by a synthetic resin elastomer or silicone resin, resulting in it being free of vinyl chloride, so that the present invention may provide a non-toxic and safe doll head which does not lead to environmental pollution and which is harmless to health of the human body. Also, the doll head is permitted to exhibit elasticity and have a soft feel like the human skin, resulting in a doll particularly suitably used as an instrument which permits infants and children to gain pseudo-experience in play being provided.
Moreover, the molded article is elastic, to thereby be readily smoothly removed from the mold, resulting in damages to undercuts of the head such as a nose, a chin or the like being prevented.
It is preferable that the split mold be formed at a portion thereof corresponding to a neck of the doll with a rod so as to be retractably advanced into the cavity, so that the rod is advanced into the cavity after blowing air and is retracted or retreated from the cavity before the mold members of the split mold are separated from each other, resulting in a neck hole being formed. Such construction prevents the neck hole from damaging the remaining part of the head, because the neck hole is by advancing the rod into the cavity of the split mold after air is blown into the cavity during the molding to expand the parison.
Removal of air from the cavity is desirably carried out through a fine air vent hole formed through the projection of the split mold. Alternatively, removal of air from the cavity may be carried out via a bar-like porous element inserted through the split mold.
In accordance with another aspect of the present invention, a mold for molding a head for a doll is provided. The mold is characterized in that the mold comprises: two split mold members of which one has an inner surface formed to have a configuration conforming to a shape of a face of the doll and the other has an inner surface formed to have a configuration conforming to a shape of a rear and side head portion of the doll, the split mold members having a parting line formed on a hairline of the hair of the head or in proximity thereto; one of the split mold members being formed at at least one of projections provided on the inner surface with an air vent means which permits air in a cavity in the split mold members to be removed therethrough when air is blown into the split mold members.
The mold thus constructed positively realizes satisfactory practicing of the above-described molding method by blow molding, so that a doll head may be formed to have a sharp configuration substantially equal to that conventionally obtained by slush molding or rotating molding. Also, one of the split mold members has the inner surface formed to have a configuration conforming to the shape of the face of the doll and the other mold member has the inner surface formed to have a configuration conforming to the shape of the rear and side head portion of the doll. This prevents a parting line from appearing on the face which is the most important portion of the doll head.
The split mold members preferably have a rod for formation of a neck hole arranged at a portion thereof corresponding to a neck of the doll in a manner to be retractably advanced into the cavity. The arrangement of the rod ensures formation of the neck hole without damaging the remaining part of the doll head. Also, the rod is preferably formed on a peripheral surface of a distal end thereof with a ring-like groove. The ring-like groove thus formed permits a peripheral surface of the neck hole of the molded doll head to be formed with an annular projection, which effectively functions to prevent a neck portion of a body of the doll fitted in the neck hole from being detached from the neck hole.
The air vent means is preferably constituted by an air vent hole formed through the split mold member and the air vent hole is preferably formed to have a diameter of from 0.1 mm to 0.3 mm. Alternatively, the air vent means may be constituted by a bar-like porous element inserted through the split mold member. In this instance, the porous element desirably has pores formed to have a diameter of from 0.03 mm to 0.1 mm. Such construction permits air in the cavity forced out due to expansion of the parison by blowing air during the molding to be naturally removed to the outside from the air vent means, so that the doll head may be formed to have a shape exactly corresponding to the inner configuration of the mold without forcible removal of the air. Also, the air vent hole or pores for air removal are formed to have a sufficiently small diameter, to thereby prevent ingress of the molding material into the air vent hole or pores during the molding, resulting in a trimming operation after the molding being eliminated.